The hypothetical language or languages spoken by the Iron Age Nordwestblock population are a matter of speculation, as there are no written records of such languages as is the case with the Germanic language, but can be inferred based on analysis of
substrate features in the primarily
West Germanic languages that later came to be spoken in the region (for example, areal
loanwords of unknown origin, and the presence of certain
geminate consonants that cannot be explained by
inheritance from
Proto-Indo-European), or by analysis of place-names (
toponymy and
hydronymy). Broadly, this substrate area is sometimes called the
North-West European substratum. Kuhn speculated on linguistic affinity of this substratum to the
Venetic language, while other hypotheses connect the Northwestblock with the
Rhaetic ("
Tyrsenian") or generic
Indo-European languages of the
centum type (
Illyrian, "
Old European"). Gysseling suspected an intermediate
Belgian language between Germanic and
Celtic, that might have been affiliated to
Italic. According to
Luc van Durme, a Belgian linguist, toponymic evidence of a former Celtic presence in the
Low Countries is almost completely absent. Kuhn noted that since, in
Proto-Indo-European (PIE), the phoneme * was very rare, and since PIE *, via
Grimm's law, is the main source of regularly inherited in words in Germanic languages (except after fricatives, e.g. initial
*sp- from PIE
*(s)p-), the many words in which occurs must have some other language as their source. Similarly, in Celtic, PIE * disappeared and in regularly-inherited words did not reappear in
p-Celtic languages except as a result of
Proto-Celtic *kʷ becoming
*p. All that taken together means that any word starting with a in a Germanic language that is not evidently borrowed from either Latin or a p-Celtic language, such as Gaulish, must be a loan from another language. Kuhn ascribes those words to the Nordwestblock language. Linguist
Peter Schrijver assumes the pre-existence of
pre-Indo-European languages linked to the archeological
Linear Pottery culture and to a family of languages featuring complex verbs spoken by the earliest Neolithic farmers, of which the
Northwest Caucasian languages might have been the sole survivors. Although assumed to have left traces within all other Indo-European languages as well, the influence of an unknown substrate would have been especially strong on Celtic languages originating north of the Alps and on the region including Belgium and the Rhineland. It is uncertain when Germanic began to gain a foothold in the area. The Nordwestblock region north of the Rhine is traditionally conceived as belonging to the realms of the Northern Bronze Age, with the Harpstedt Iron Age generally assumed to represent the Germanic precedents west of the
Jastorf culture. The general development converged with the emergence of Germanic within other previously Northern Bronze Age regions to the east, maybe also involving a certain degree of Germanic cultural diffusion. From about the 1st century CE, that region saw the development of the "
Weser–Rhine" group of West Germanic dialects which gave rise to
Old Frankish from the 4th century. The issue still remains unresolved and so far no conclusive evidence has been forwarded to support any alternative.
Mallory considers the issue a salutary reminder that some anonymous linguistic groups that do not fully obey the current classification may have survived to the beginning of historical records. == Prehistoric composition ==